Liquid-liquid equilibrium of the system glycerolized olive oil + ethanol + glycerol for diacylglycerol enrichment

Edible oils enriched with diacylglycerols are promising choices for healthy cooking oils, and for that reason production and separation processes regarding these molecules have received great attention. This work reports experimental results and thermodynamic modelling of liquid-liquid equilibrium of systems containing glycerolized olive oil (source of triacylglycerols, diacylglycerols, monoacylglycerols and free fatty acids), glycerol and ethanol. The LLE experimental data were used to estimate UNIQUAC binary interaction parameters. The mathematical model calculated the liquid phase’s compositions by minimizing the Gibbs free energy of the system, using a combination of stochastic and deterministic optimization methods in order to avoid local minima. The model was well fitted to the experimental data, with a root mean square deviation of 1.43 wt% between experimental and calculated data. The results indicate the feasibility of diacylglycerol separation from other triacylglycerols and free fatty acids through liquid-liquid phase separation using glycerol and ethanol as solvents.